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ENDOCRINE SYSTEM

ENDOCRINE SYSTEM. TYPES OF GLANDS. Endocrine Exocrine. Pineal gland Pituitary gland Thyroid gland Parathyroid glands Thymus Adrenal gland Pancreas Ovaries / Testes. Stomach Duodenum Kidney. Endocrine glands; Endocrine tissue. Chemistry of Hormones.

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ENDOCRINE SYSTEM

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  1. ENDOCRINE SYSTEM

  2. TYPES OF GLANDS Endocrine Exocrine

  3. Pineal gland Pituitary gland Thyroid gland Parathyroid glands Thymus Adrenal gland Pancreas Ovaries / Testes Stomach Duodenum Kidney Endocrine glands; Endocrine tissue

  4. Chemistry of Hormones • Amines - simple hormones synthesized from tyrosine • Proteins and Peptides - chains of amino acids hooked together • Steroids - lipid soluble hormones derived from cholesterol • Eicosanoids - hormones derived from arachidonic acid (from lipids)

  5. Mechanisms of Hormone Action • Alters plasma membran permeability • Stimulates synthesis of protein • Activates or deactivates enzymes • Induces secretory activity • Stimulates mitosis

  6. Lipid Soluble Hormones • Thyroid and steroid hormones cross the cell membrane and bind to INTRACELLULAR receptors in the cytoplasm or nucleus • The hormone- receptor complex triggers activation or inactivation of specific genes • Synthesis of new protein alters cellular activity causing a physiological response

  7. Water Soluble Hormones • Protein and catecholamine hormones act by binding to receptors located on the cell membranes of target cells • Hormones act as the 1st messenger which in turn activates a series of events involving cAMP as the 2nd messenger • cAMP activates protein kinases • G-proteins link the first messenger and the second messenger

  8. Hormone Release • Humoral - hormones released in response to changing blood levels • Neural - nerve fibers stimulate release • Hormonal - one hormone stimulates the release of another

  9. Endocrine Glands

  10. Pituitary Gland • Master gland • Located within the sella turcica of the sphenoid bone • Associated closely with the hypothalamus • Differentiated into the anterior pituitary, or glandular portion, the posterior pituitary, or nervous portion and the avascular pars intermedia located in between

  11. Posterior lobe - Neurohypophysis • Connected with the hypothalamus via the supraopticohypophyseal tract • Oxtocin (OT) • Antidiuretic hormone (ADH) • diabetes insipidus

  12. Anterior lobe (Adenohypophysis) • Controlled by releasing and inhibiting hormones produced by the hypothalamus • Growth hormone (GH) • somatotropin • dwarfism, giantism, acromegaly • Thyroid - stimulating hormone (TSH) • Adrenocorticotropic hormone (ACTH)

  13. Acromegaly

  14. Anterior lobe of the Pituitary • Follicle - stimulating hormone (FSH) • Luteinizing hormone (LH) • Prolactin (PRL) • Melanocyte - stimulating hormone (MSH)

  15. Thyroid Gland • Located below the larynx, two lobes connected by an isthmus • Hormones synthesized from iodine and tyrosine • Follicle cells manufacture thyroglobin and store it as colloid • Triiodothyronine (T3) / Thyroxine (T4) • Goiter, Graves Disease, Cretinism, Myxedema • Calcitonin (CT) - lowers calcium levels

  16. Parathyroid gland • Four tiny glands located on posterior thyroid • Parathyroid hormone (PTH) • Raises blood calcium

  17. Adrenal Glands • Located retroperitoneally and superior to the kidney • Can be subdivided into outer cortex and inner medulla

  18. Adrenal Medulla • Consists of hormone-producing cells called chromaffin cells • Epinephrine / Norepinephrine (NE) • Sympathomimetic hormones • Released under stress by direct innervation from the autonomic nervous system

  19. Adrenal Cortex • Manufactures steroid hormones called corticosteroids • Divided into three regions: zona glomerulosa, zona fasciculata, zona reticularis • Zona glomerulosa (outer) - releases mineralocorticoids, principally aldosterone which controls electrolyte balance in the kidneys

  20. Adrenal Cortex • Zona fasciculata (middle) - produces glucocorticoids such as cortisol and cortisone; controlled by ACTH • Addison’s Disease, Cushing’s Disease • Zona reticularis (inner) - produces adrenal sex hormones such as estrogens and androgens • virilism, gynecomastia

  21. Cushings Disease

  22. Located posterior to the sternum and between the lungs Thymosin Located in the roof of the 3rd ventricle of the brain Melatonin Thymus Pineal Gland

  23. Pancreas • Located posterior and inferior to the stomach • Both exocrine and endocrine • Islets of Langerhans • Alpha cells - glucagon • Beta cells - insulin • Delta cells - somatostatin • Diabetes mellitus - Type I, TypeII

  24. Ovaries • Located in the pelvic cavity • Estrogens • Estradiol, estriol, estrone • Progesterone • Inhibin • Relaxin

  25. Testes • Located in the scrotum • Testosterone • Inhibin

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